Chemical, Biological, Radiological, and Nuclear Weapon Detection System with Alarm Thresholds Based on Environmental Factors

1. A system comprising: a first environmental sensor for monitoring a first environmental characteristic; a first hazardous material sensor for measuring the amount of a first hazardous material; and a first alarm that is issued when the amount of said first hazardous material reaches a first threshold, wherein said first threshold changes and is based on said first environmental characteristic.

2. The system of claim 1 wherein said first environmental characteristic is precipitation.

3. The system of claim 2 wherein said first threshold is higher when it is precipitating than when it is not precipitating.

4. The system of claim 1 wherein said first environmental characteristic is humidity.

5. The system of claim 4 wherein said first threshold is higher when it is lower humidity than when it is higher humidity.

6. The system of claim 1 wherein said first environmental characteristic is sunlight.

7. The system of claim 6 wherein said first threshold is higher when it is night than when it is day.

8. The system of claim 1 wherein said first environmental characteristic is wind speed.

9. The system of claim 8 wherein said first threshold is higher when it is windy than when it is not windy.

10. The system of claim 1 further comprising a second environmental sensor for monitoring a second environmental characteristic; wherein said first threshold changes and is based on said first environmental characteristic and on said second environmental characteristic.

11. The system of claim 1 further comprising: a second hazardous material sensor for measuring the amount of a second hazardous material; and a second alarm that is issued when the amount of said second hazardous material reaches a second threshold, wherein said second threshold changes and is based on said first environmental characteristic.

12. A method comprising: monitoring a first environmental characteristic; measuring the amount of a first hazardous material; and issuing a first alarm when the amount of said first hazardous material reaches a first threshold, wherein said first threshold changes and is based on said first environmental characteristic.

13. The method of claim 12 wherein said first environmental characteristic is precipitation.

14. The method of claim 13 wherein said first threshold is higher when it is precipitating than when it is not precipitating.

15. The method of claim 12 wherein said first environmental characteristic is humidity.

16. The method of claim 15 wherein said first threshold is higher when it is lower humidity than when it is higher humidity.

17. The method of claim 12 wherein said first environmental characteristic is sunlight.

18. The method of claim 17 wherein said first threshold is higher when it is night than when it is day.

19. The method of claim 12 wherein said first environmental characteristic is wind speed.

20. The method of claim 19 wherein said first threshold is higher when it is windy than when it is not windy.

21. The method of claim 12 further comprising: monitoring a second environmental characteristic; wherein said first threshold changes and is based on said first environmental characteristic and on said second environmental characteristic.

22. The method of claim 12 further comprising: measuring the amount of a second hazardous material; and issuing a second alarm when the amount of said second hazardous material reaches a second threshold, wherein said second threshold changes and is based on said first environmental characteristic.